Directional drilling has proven useful in facilitating the production of formation fluid, e.g., hydrocarbon-based fluid, from a variety of reservoirs. In application, a vertical wellbore is drilled, and directional drilling is employed to create one or more deviated or lateral wellbores extending outwardly from the vertical wellbore. Often, a whipstock is employed to facilitate the drilling of the one or more lateral wellbores in a method referred to as sidetracking.
If the formation being drilled is hard or formed of abrasive rock, diamond impregnated drill bits are used. The cuffing face of diamond impregnated drill bits include diamonds, e.g., natural or synthetic diamonds, which are distributed through a supporting material, sometimes referred to as matrix material. The distributed diamonds form an abrasive layer, and during operation of the drill bit, the diamonds within the abrasive layer become exposed as the supporting material wears away. As the supporting material continues to be worn away, new diamonds are exposed to enable long-term cutting capability for the diamond impregnated drill bit.
To facilitate directional drilling with an impregnated drill bit, the whipstock is used to guide the drill bit in a lateral direction to establish a lateral or deviated wellbore branching from the existing substantially vertical wellbore. Whipstocks are designed with a face, or ramp surface, oriented to guide the drill bit in the desired lateral direction. The whipstock is positioned at a desired depth in the wellbore and its face oriented to facilitate directional drilling, i.e., sidetracking, of the lateral wellbore along the desired drill path. In many applications, sidetracking requires at least two trips downhole. In an initial trip, a short multi-ramp whipstock is delivered downhole, oriented and set at the desired wellbore location. A bi-mill is then used in conjunction with the short multi-ramp whipstock to enable drilling of a few feet of rat hole. The bi-mill is then tripped out of the wellbore. In a subsequent trip, a drilling bottom hole assembly, with an impregnated drill bit and a turbodrill, is tripped downhole to complete the drilling of the lateral wellbore. However, each trip downhole beyond the initial trip increases both the time and costs associated with the drilling operation.